A crop of photovoltaic panels—33,500 of them—packs one of the world's largest solar parks, outside Leipzig, Germany. The panels produce up to five megawatts of electricity and average enough to supply 1,800 homes. Solar technology remains expensive and can't compete on a large scale against cheaper fossil fuels without serious government subsidies. Still, the cost of solar is expected to decrease, and this promising power source is making inroads in developed and developing nations alike. In rural Kenya, for example, where many people live far from power grids, roughly 20,000 small-scale solar systems are purchased each year.